1. Field of the Invention
This invention is concerned with the art of forming traffic dividing and regulating lines on roadway pavements, such as center or edge lines, or traffic lane dividing lines along a roadway or highway.
2. Description of the Prior Art
This art is a widely known and well worked one and a variety of machines for forming said lines, either in continuous or interrupted manner, that is by forming aligned spaced lengths of the line, as most common in traffic lane dividing lines. A large patent and technical literature exists for the art. These lines can be formed by making use of different methods.
The older but still applied method comprises forming the line by spraying paint in printed or other forms on the roadway pavement and many machines for quickly and economically performing such operation have been devised. The British Pat. Specification No. 410,094, published on 1934, might be considered a basic one in the art, which has been substantially and continuously improved. One improvement consists in spraying retroreflective beads on the freshly applied paint for improving visibility in particular nighttime visibility to the marking line. Efficient machines for continuously or programmedly discontinuously forming marking lines, by painting, are manufactured by several manufactures and available on trade.
Another method for forming road marking lines consists of forming the line of the line lengths by applying thermoplastic substance in heat liquified or plasticized status on the road pavement and causing the same to harden thereon at the desired location and configuration. This method also is old, such as described in the U.S. Pat. No. 1,726,832, issued on Sept. 3, 1929. Consistently improved machines have been and are produced and available on the market.
Machines for forming continuous or programmedly discontinuous road marking lines on the surface of a roadway pavement are produced and sold by a plurality of manufacturers, such as for example Wilson & Scott Ltd, of Chertsey, Surrey (Breat Btitain), Hofmann Universal-Markiermaschine, of Hamburg (West Germany) and many others.
No problem therefore exists as to the availability and the operations concerned with the machines and the forming of marking lines by applying the above methods.
A third method comprises factory producing and winding into bobbins a prefabricated tape material adapted for being laid on and adhesively secured to the roadway pavement, upon a tape receiving under-layer (or "primer" layer), suitable machines being provided for forming the marking line on said pavement by progressively unwinding the tape, cutting the same into suitable long lengths, when a discontinuous line is to be formed.
This third method has been principally developed and improved by the Applicant of the application. In the U.S. Pat. No. 3,007,838 there has been a first embodiment of a tape applying and marking line forming apparatus. Subsequent U.S. Pat. Nos. 3,155,564, 3,235,436, 3,844,669, 3,886,011, 3,964,559 and 3,964,835 have described and shown many omprovements and details of such machines, including mechanisms for progressing and cutting the tape material, for pressuredly applying it on the roadway pavement, more particularly on an under-layer and for preliminarily forming said under-layer or primer layer on the road surface.
Concurrently with the development and improvement of the machines and the operations for applying the tape material to the road surface, said tape materials have been developed and successively improved, either as to their properties of being firmly and durably secured to the road surface, and as to their properties of ensuring the best nighttime visibility, under the illumination provided by the "grazing" light emitted by the head lamps of the travelling cars and vehicles, this visibility being evidently essential for traffic safety.
The art most principally related to the road marking tape material has been principally described in the following U.S. Pat. Nos. 3,262,375, 3,399,607, 3,587,415, 3,782,843, 3,879,148, 3,958,891 and 4,020,211. A number of composition adapted for forming the tape materials, the elements secured to the upper face of the tape for light impingement and reflection and so on, have been described.
Generally, the primer layer is formed and caused to at least partially set on the road surface and then the tape material is laid thereon. A new approach for further improving this art has been described and made open to public in the published German Patent Application P 27 02 442.6 and in the French Patent Publication No. 77.04466 of the present applicant. (U.S. Pat. No. 4,102,718).
According to this recent proposal, a composite tape material is provided including juxtaposed layers, more particularly an upper layer (assuming that the multi-layer has been applied) comprising all components and elements as necessary for providing traffic wear resistance, and principally daytime and nighttime visibility, and at least a lower layer adapted to from the under-layer or primer layer for the road marking tape material.